Re: [RESEND PATCH v5 5/5] input: joystick: Add ADC attached joystick driver.

[Paul Cercueil]

Le sam. 18 avril 2020 à 14:57, Andy Shevchenko 
<andy.shevchenko@xxxxxxxxx> a écrit :
> On Sat, Apr 18, 2020 at 1:48 AM Paul Cercueil <paul@xxxxxxxxxxxxxxx> 
> wrote:
> >  Le sam. 18 avril 2020 à 0:49, Andy Shevchenko
> >  <andy.shevchenko@xxxxxxxxx> a écrit :
> >  > On Sat, Apr 18, 2020 at 12:24 AM Paul Cercueil 
> > <paul@xxxxxxxxxxxxxxx>
> >  > wrote:
> >  >>  Le sam. 18 avril 2020 à 0:10, Andy Shevchenko
> >  >>  <andy.shevchenko@xxxxxxxxx> a écrit :
> >  >>  > On Fri, Apr 17, 2020 at 11:21 PM Artur Rojek
> >  >> <contact@xxxxxxxxxxxxxx>
> >  >>  > wrote:
> >  >
> >  > ...
> >  >
> >  >>  >>  +#include <linux/of.h>
> >  >>  >
> >  >>  > Do you really need this? (See below as well)
> >  >
> >  >>  >>  +static const struct of_device_id adc_joystick_of_match[] = 
> > {
> >  >>  >>  +       { .compatible = "adc-joystick", },
> >  >>  >>  +       { },
> >  >>  >>  +};
> >  >>  >>  +MODULE_DEVICE_TABLE(of, adc_joystick_of_match);
> >  >>  >>  +
> >  >>  >>  +static struct platform_driver adc_joystick_driver = {
> >  >>  >>  +       .driver = {
> >  >>  >>  +               .name = "adc-joystick",
> >  >>  >
> >  >>  >>  +               .of_match_table =
> >  >>  >> of_match_ptr(adc_joystick_of_match),
> >  >>  >
> >  >>  > Drop this a bit harmful of_match_ptr() macro. It should go 
> > with
> >  >> ugly
> >  >>  > #ifdeffery. Here you simple introduced a compiler warning.
> >  >>
> >  >>  I assume you mean #ifdef around the of_device_id + module table
> >  >> macro?
> >  >
> >  > Yes.
> >  >
> >  >>  > On top of that, you are using device property API, OF use in 
> > this
> >  >> case
> >  >>  > is contradictory (at lest to some extend).
> >  >>
> >  >>  I don't see why. The fact that the driver can work when probed 
> > from
> >  >>  platform code
> >  >
> >  > Ha-ha, tell me how. I would like to be very surprised.
> >
> >  iio_map_array_register(),
> >  pinctrl_register_mappings(),
> >  platform_add_devices(),
> >
> >  you're welcome.
>
> I think above has no relation to what I'm talking about.

Yes it does. It allows you to map the IIO channels, set the pinctrl 
configurations and register a device from platform code instead of 
devicetree.

> How *this* driver can work as a platform instantiated one?
> We seems have a conceptual misunderstanding here.
>
> For example, how can probe of this driver not fail, if it is not
> backed by a DT/ACPI properties?

platform_device_add_properties().

> >  >>  doesn't mean that it shouldn't have a table to probe
> >  >>  from devicetree.
> >  >
> >  > I didn't get what you are talking about here. The idea of 
> > _unified_
> >  > device property API is to get rid of OF-centric code in favour of 
> > more
> >  > generic approach. Mixing those two can be done only in specific 
> > cases
> >  > (here is not the one).
> >
> >  And how are we mixing those two here? The only OF-centric thing 
> > here is
> >  the device table, which is required if we want the driver to probe 
> > from
> >  devicetree.
>
> Table is fine(JFYI the types and sections are defined outside of OF
> stuff, though being [heavily] used by it) , API (of_match_ptr() macro
> use) is not.

Sorry, but that's just stupid. Please have a look at how of_match_ptr() 
macro is defined in <linux/of.h>.

-Paul